The investigator's group has surmounted some cloning barriers and has succeeded in identifying two virtually identical enhancers, one located approximately 10 kb 3' of each of the two human C alpha genes. These enhancers contain a 191 bp segment of homology to the murine enhancer 3'aE (Hst2). They wish to study the regulation of the human C alpha associated enhancers, to further map these downstream regions and assess them for additional enhancers which they predict to be present, and to acquired variations that influence IgH gene expression in normal, immunodeficient and malignant states.